Advances in electronic technology cause integrated circuits to be formed on substrates such as silicon wafers with ever increasing packing density of active components. The formation of circuits is carried out by sequential application, processing, and selective removal of various components from the substrate. Various compositions have been developed for removal of specific classes of components from substrates in semiconductor wafer technologies. For example, a composition commonly denoted SC-1, which contains a mixture of NH4OH(29 wt %)/H2O2(30 wt %)/water at a volume ratio of about 1:1:5 (or at somewhat higher dilution ratios), is typically used to remove particles and to reoxidize hydrophobic silicon surfaces. Similarly, a composition commonly denoted SC-2, which contains a mixture of HCl(37 wt %)/H2O2(30 wt %)/water at a volume ratio of about 1:1:5 (or at somewhat higher dilution ratios), is typically used to remove metals. An additional composition, commonly called SPM or a Piranha composition, comprises H2SO4(98 wt %)/H2O2(30 wt %) at a volume ratio of about 2:1 to 20:1, and is typically used to remove organic contamination or some metal layers.
U.S. Pat. No. 7,592,264 describes a method of removing materials, preferably photoresist, from a substrate. The method includes dispensing a liquid sulfuric acid composition comprising sulfuric acid and/or its desiccating species and precursors. The entire contents of this patent is hereby incorporated by reference. Removing photoresist is also disclosed in WO 2008/143909, the entirety of which is incorporated herein by reference.
In addition to photoresist, there are other well known materials such as carbon materials (e.g., amorphous carbon, diamond-like carbon, and/or graphitic carbon) that can be used in many circuit manufacturing processes. For example, such materials may be used to assist in formation of sequential layers. In stages of the manufacturing process, at least a portion of some of these materials are often removed, preferably without substantial damage to the substrate, including structures formed thereon. It is noted that carbon materials such as amorphous carbon, diamond-like carbon, and/or graphitic carbon materials are distinct from photoresist material. For example, the article “Characterization of 248 nm Deep Ultraviolet (DUV) Photoresist after ion Implantation” reports that while photoresist was detected (e.g., in FIG. 4), no experimental evidence was found for the presence of amorphous carbon.
It would be desirable to identify alternative techniques and compositions for treatment to remove at least a portion, preferably all, of carbon materials, especially amorphous carbon materials from substrates such as semiconductor wafers.